Although there have been many changes and improvements in vehicle cooling systems for internal combustion engines over the last few decades, the wax pill actuated coolant valve (thermostat) has remained basically unchanged since its inception. With the increase in government mandated fuel economy regulations, companies are increasingly looking for new technology that will reduce the parasitic losses and improve efficiency of internal combustion engines. Furthermore, the introduction of hybrid and full electric vehicle powertrains has introduced new powertrain coolant and thermal management complexities due to the need to control the temperature of batteries, inverter electronics, eMotors, etc. These trends lead to the need for more intelligently controlled coolant valves.
Some thermostat valve manufacturers have introduced a heated wax design in which a heating element is used to expand the wax to open the valve. This provides a direct electric actuation mechanism, but does not provide for precise control. Other valve manufacturers have prototype designs which use a brushless DC (BLDC) motor and gear train for actuating the valves. There also is a controlled coolant valve design that employs a rotary design actuated by a BLDC gearmotor.